The present invention relates to damping devices for transmitting torque between an input part and an output part which can rotate relative to each other and also for absorbing or compensating for torque fluctuations. Typically such damping devices can be used in vehicle transmissions for example as part of a twin mass fly wheel or in a torque converter or used on their own in a vehicle drive line.
It is an object of the present invention to provide an improved form of damping device which causes a resistance to relative rotation of input and output parts which varies dependant upon the angular position of the input part relative to the output part.
Thus, according to the present invention there is provided a damping device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to the first part and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts and a resilient means acting generally circumferentially between the linkage device and the first part to resist relative rotation of the first and second parts.
According to a further aspect of the invention there is also provided a damping device including co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, the damping device also including at least one linkage device comprising an anchor link pivotally connected via a first pivot to the first part, and having a torque transmitting connection with the second part, the linkage device acting to resist relative rotation of the first and second parts, and the first pivot being resiliently mounted on the first part.
According to a still further aspect of the invention there is provided a damping device comprising co-axially arranged first and second parts which can rotate relative to each other by a limited amount about an axis of the damping device, and having damping means acting to resist relative rotation of the first and second parts, stops being provided on the first and second parts respectively which come into contact to substantially limit the relative rotation of the two parts, in which at least one of the stops is resiliently mounted to its respective part so as to permit a further limited amount of relative rotation of the two parts following contact between the stops.
The generally circumferentially acting resilient means of the above first statement of invention, the resilient mounting of the first pivot on the first part of the above second statement of invention and the resilient mounting of one of the stops of the above third statement of invention are all independently applicable to the embodiments shown in prior patent applications PCT/GB96/01282, PCT/GB97/00361, GB 9709436.1 and GB-A-2313898.